DANIA BEACH, Fla. (AP) — The Coast Guard is suspending its search for two people still missing after their Mexico-bound jet crashed into the Atlantic Ocean off South Florida, officials announced Thursday evening.

During a news conference in Dania Beach with the Coast Guard and the Mexican consulate, Lt. Cmdr. Gabe Somma said the Coast Guard will continue to assist the National Transportation Safety Board by recovering debris but will no longer search for the missing victims.

“There have been no signs of survivors,” Somma said. “Survivability beyond this time is highly unlikely.”

The Learjet 35 crashed Tuesday night into the ocean about a mile offshore, and authorities have recovered the bodies of two other people from the wreckage.

The search has covered 4,000 square miles, Somma said. More than 1,000 pounds of debris has been located and recovered for the NTSB’s investigation.

Two pilots, a doctor and a nurse were on the plane. They were flying back to Cozumel, Mexico, when the pilot reported an engine failure and attempted to return to the airport.

NTSB investigator Brian Rayner said it’s still unclear what caused the crash. Of the debris that’s been found, there’s no evidence of a fire, he said. Everything seems consistent with a water impact, but neither engine has been recovered. No flight recorder has been recovered, and officials haven’t been able to determine whether the plane had one.

“At this stage in the investigation, what I’m interested in is the gathering of evidence,” Rayner said. “The more we gather, the more we can rule out.”

Mexico’s Transportation Department has identified the pilots as Jose Hiram Galvan de la O. and Josue Buendía Moreno and the passengers as Fernando Senties Nieto and Mariana Gonzalez Isunza. It was not immediately clear which victims remained missing Thursday.

The company that runs the medical transport planes said the flight crew had picked up a patient in Costa Rica.

Francisco de la Lama, the deputy general consul of Mexico in Miami, said family members of all four victims have come to South Florida.

“As you can imagine, they’re very devastated,” de la Lama said.

Federal Aviation Administration officials had warned of potential problems found in the Learjet 35 in June.

According to the special bulletin, maintenance workers found cracks in the control column on Learjet Model 35A (C-21A) airplanes. Five airplanes were inspected and all five had cracks in the area at the base of the column where it attaches to the floor. However, the concern was not deemed dangerous enough to warrant a further directive, according to the bulletin.